Conventionally, there is known a sheet post processing apparatus which is attached to an image forming apparatus and sequentially receives the sheet discharged from the image forming apparatus and then carries out a sheet post processing. There is a glue binding processing apparatus which has one of the functions of the sheet post processing apparatus to bind a plurality of sheets with glue into one bundle.
The glue binding processing apparatus carries out a processing in which the sequentially received sheets are discharged to and stacked on the processing tray, glue (liquid glue, solid glue, tape glue and the like) is adhered to the part equivalent to a given binding margin of the sheet placed on the processing tray, and then a next sheet is to be placed thereon. In the end, the sheet of the last page is placed on the previous sheet, and in this way, the glue binding is ended.
The glue binding processing apparatus is provided with a cradle that receives a pressing force at the back side of the sheet when glue material is adhered to the sheet so that glue can be adhered to the sheet with sufficient pressing force.
Further, glue is adhered to the sheet at a timing matching with a given timing when the sheet is received from the image forming apparatus.
On the other hand, in a case in which the first sheet to be sent to the processing tray doesn't reach the position of the processing tray where glue is adhered, or in a case in which the corner of the sheet is folded and there is no binding margin part on the cradle, if the operation for adhering glue is executed, the glue is directly adhered to the surface of the cradle.
If the glue is adhered to the surface of the cradle, there is a possibility that a second sheet is stuck to the cradle and the sheet bundle may not be generated. Further, the second sheet may be stuck to the cradle and a paper jam (JAM) may occur.